// dot 画出的圆点, 即使图像缩放, 仍然保持圆形.
// 注意 x y轴的尺寸分别为 50, 10
settings.outformat = "pdf";
size(5cm, 5cm, keepAspect = false);
draw((0, 0)--(50, 0), arrow = Arrow(TeXHead));
draw((0, 0)--(0, 10), arrow = Arrow(TeXHead));
dot((2, 1));
dot((35, 8));
dot((42, 9), red);